1. Field of the Invention
The present invention relates to an X-ray waveguide, in particular, an X-ray waveguide used in an X-ray optical system, for example, in an X-ray analysis technology, an X-ray imaging technology, or an X-ray exposure technology.
2. Description of the Related Art
When an electromagnetic wave having a short wavelength of several tens of nanometers or less is dealt with, a difference in refractive index for any such electromagnetic wave between different materials is extremely small, specifically, 10−4 or less, and thus, for example, a critical angle for total reflection becomes extremely smaller. In view of the foregoing, a large-scale spatial optical system is usually used for controlling such an electromagnetic wave including an X-ray. Among the main components of which the spatial optical system is formed, multilayer mirrors obtained by alternately laminating materials having different refractive indices are playing various roles such as beam shaping, spot size conversion, and wavelength selection.
A conventional X-ray waveguide such as a polycapillary propagates, in contrast to such mainstream spatial optical system, an X-ray by confining the X-ray in itself. Researches have been recently conducted on X-ray waveguides propagating X-ray by confining the X-ray in a thin film or a multilayer film, with a view to reducing the size and improving the performance of an optical system.
Specifically, researches have been conducted on, for example, thin-film waveguides of such a constitution that a waveguiding layer is interposed between two layers of one-dimensional periodic structures (see Physical Review B, Volume 67, Issue 23, p. 233303 (2003)), and an X-ray fiber of such a constitution that a vacuum core is surrounded with a cladding obtained by alternately laminating a heavy element and a light element (see Japanese Patent Application Laid-Open No. H03-146909).